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I am thinking about being in a study at our university hospital for my back and leg pain. They are comparing steroid injections to surgery for patients like me with lumbar spinal stenosis. As part of the paperwork I read this morning, I have the right to crossover. I didn't think much about it at the time, but now I'm wondering -- what does that mean?

Crossover refers to patients who start in one group (e.g., injection group) and end up going (crossing over) to the surgical group (or vice versa). Since you are participating in this study comparing epidural steroid injection with surgery, you might find the results of a recent (similar) study of interest. In this study, results for patients who received ESI for their symptomatic (with symptoms) lumbar stenosis were compared with outcomes of patients who did NOT receive the injection. Everyone in both groups did have painful neurologic symptoms and had tried at least three months of nonoperative care without success. The type of conservative care they received included home exercise, nonsteroidal antiinflammatory drugs, education and counseling, and active physical therapy. The researchers were very thorough in examining characteristics of patients and any factors that might affect the results. They looked at age, smoking status, general health, presence and types of other health problems, marital status, work or employment, income, education, race, body mass index, and many other variables. Details of the symptoms and stenosis (location in the spine, severity, duration, affect on activities) were also recorded and analyzed. Anyone who ended up having surgery (from either group -- those who had the steroid injection and those who didn't) were also examined carefully. Information was collected on type of surgery, length of stay in the hospital, postoperative complications, additional surgeries, blood loss, and number of minutes in surgery. In the end, they found that patients who had the epidural steroid injections (ESI) during the four year study period had significantly less improvement in symptoms over anyone else. That included patients who had surgery (and those who didn't have surgery). The main conclusion of this study was that patients with lumbar spinal stenosis who have ESI have worse results than those who don't have ESI. A second observation from the study was related to patient crossover. The surgical group had better results than the injection group. So the patients who crossed over from originally being in the surgical group to the injection group may have had worse results than if they had stayed in the surgical group. Patients in the ESI group who had the injection and then crossed over to have surgery also had worse results than the surgical group who did not have any injections. The surgery took longer for the ESI-crossover-to-surgery group. They were also in the hospital longer without any measurable benefit from the procedure. With all that data collected, the authors went digging for an explanation. Other studies have suggested that earlier treatment with ESI might make a difference. Obesity and emotional instability have been linked with poorer results using ESI. Sometimes outcomes are significantly worse when patients have both stenosis AND lumbar disc degeneration. The possible explanations offered by this group of researchers included: 1) adding fluid from the injection to an already narrow spinal canal may make the symptoms worse instead of better, 2) the steroid drug may damage nerve roots, and 3) the injected substances (numbing agent and steroid) may be viewed by the body as "toxic" and cause direct injury to nerve cells and/or scar tissue to form around the nerve tissue. In the end, from this study it looks like epidural steroid injection for lumbar spinal stenosis may not be the best way to avoid surgery. The surgical group had better results than the injection group. So the patients who crossed over from originally being in the surgical group to the injection group may have had worse results than if they had stayed in the surgical group. Future studies may be able to determine who would be a good candidate for ESI before surgery (and who should go from conservative care to surgical care without ESI). Until patient selection for ESI versus surgery is clearly determined, patients should be advised that choosing ESI to avoid surgery isn't always the best option.

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